FORCED-OSCILLATIONS OF AIRFOIL FLOWS

The effect of background how oscillations on a transonic airfoil (NACA 0012) flow was investigated experimentally. The oscillations were gen erated by means of a rotating plate placed downstream of the airfoil. Owing to the expansion and compression waves generated at the plate, t he flow over the airfoil flow was drastically disturbed. This resulted in the presence of high intensity oscillations of a shock wave and a separation bubble on the suction surface of the airfoil. For relativel y large values of the airfoil angle of attack, weak shock waves (trans onic sound waves) were periodically shed upstream of the airfoil.